Oyunuma Pond (Niseko Yumoto Onsen)

Oyunuma is a dramatic hot spring pond located along the scenic Panorama Line that runs between Iwanai and Niseko towns. This geothermal feature was formed by a combination of rainfall, inflow from the Yunokawa (Yusanbetsu River), and the continuous release of high-temperature sulfur gases and thermal steam from beneath the pond.

Stretching about 200 meters in circumference, the waters of Oyunuma are heated to around 60°C (140°F) by 120°C gases that erupt from fumaroles on the pond floor. These vents also release large volumes of sulfur hot spring water—approximately 1,000 liters per minute. The air is thick with the strong scent of sulfur, and steam constantly rises from the pond’s gray-black surface, which is rich in sulfuric minerals. Yellow, spherical sulfur particles floating on the surface are considered scientifically rare and valuable.

Oyunuma offers a unique visual experience, blending its geothermal mystique with the beauty of Niseko’s seasonal scenery. From the steamy pond, you can catch views of the surrounding Niseko mountain range. The sight of white steam against the lush greens of summer or the fiery reds and golds of autumn foliage creates a striking, unforgettable contrast.

Once a powerful geyser that shot water several meters high, Oyunuma's eruptions ceased due to structural changes during sulfur extraction operations in the past. Today, it serves as the primary source for Yumoto Onsen, supplying natural hot spring water to nearby bathing facilities.